In the simulator field, visual images are often generated using a camera model board system in which a television camera views a reduced scale terrain model through an optical instrument or probe. Low altitude operation implies a close approach distance to the model board surface, frequently measured in actual distances in the order of hundredths of an inch. Therefore, an effective probe impact sensor device is needed to permit prolonged operation in this area without the risk of damage to the optical probe or to the model board surface when a trainee makes a mistake.
The invention set forth herein is adapted to operate uniquely with and to supplement the invention of Richard B. Mallinson, Ser. No. 35,877 filed May 3, 1979, and assigned to the assignee of the present invention.
While the above-identified Mallinson invention is capable of measuring distances with a high degree of accuracy and precision, it is more effective when the probe is moving in a single direction. Therefore, it would not be as effective to avoid damage to the probe, or to the model board surface, in the event that the simulated vehicle, such as a helicopter, an underwater vehicle, a space vehicle, or the like, moved in any other direction, such as sideways. What is needed, therefore, is an impact sensor device to supplement the distance sensor device of the referenced invention.
The rigid requirements for realism in aircraft simulator visual systems creates difficulties in protecting the optical probe used in camera model visual systems from accidental damage. A servo driven camera and optical probe must move within such close proximity to a fixed terrain model. To prevent accidental contact and possible damage to the model or to the optical probe, many previous ideas have been proposed and considered. Earlier devices all have had one or more of the following deficiencies:
1. The sensor device was not capable of sensing in all directions or did not have the same sensitivity in all directions.
2. The sensor device was unreliable and could be damaged too easily when contact occurred.
3. The sensor device required frequent adjustments.
4. The sensor device was susceptible to false triggering.
5. The sensitivity of previously proposed sensor devices was inadequate.
6. The size of most previously proposed sensor devices was unacceptable and difficult to use with existing optical probes.
7. The complexity and/or cost of previously proposed sensor devices is prohibitive.
A device in accordance with the present invention reduces or eliminates all of the above-listed fundamental defects and admits of several other advantages as will become more apparent as the description unfolds.